I been flying Phantom 2 Vision + quadcopters for two years and never had any major issues with flying. About a week ago I did the compass calibration and the normal checks before I flying and ran into an issue with the quadcopter. I did the calibration in the same spot that I always do on the cement beside the pool and never had an issue at this location before. Normally I do the calibration , check the satellite connection before taking off (Showed seven satellites connected), maked sure it shows ready to fly and take off straight up to just 30 - 40 ft to let it sit for a few seconds hovering. However this time when I took off it started to yaw quickly left. I tried to fight to get control of it but it still wanted to go in that direction. In the end the only thing that saved me from completely losing it was to finally do a hairy crash through a tree and into a tall metal chain link fence. The top and bottom shells ended up cracked and I already bought a shell to do a shell replacement however the quadcopter still has the same issue. A few day after the crash I tried to calibrate the quadcopter and do a test flight but it still has the same issue. I didn't want to do the shell replacement and risk cracking another shell until I figured out why it's got this issue. Any advice on this issue? Thanks for all your help.